Light-distributing device.



D. CROWNFIELD.

LIGHT DISTRIBUTINGFDEVICE.

APPLICATION FILED ocr. 1a. 1911.

Patented June 25, 1918- DAVID CROWNFIELD, F CAMBRIDGE, MASSACHUSETTS.

LIGHT-DISTRIBUTIN G DEVICE.

Specification of Letters Patent. Patented June 25, 1918.

Application filed October 18, 1917. Serial No. 197,357. I

To all whom it may concern: I

Be it known that 1, DAVID CRowNFmLD, a citizen of the United States of America, and resident of Cambridge, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Light-Distributing Devices, of which the following is a specification.

This invention relates to means for effective and economic distribution of light.

ing fixture, such as a tableor stand lamp,

and to provide simple and durable structures, adapted to be made ornamental, to serve these purposes. I will describe my invention in connection with a portable stand lamp having an incandescent electric lam mounted therein but it will be understoo that the source of light may be a gas mantle, gas or oil flame, or other ordinary means of producing light, and that the mechanical and optical constructions described in order to illustrate instances of the invention are specific instances only of the genus of constructions which my invention includes.

In the accompan ing drawings,- Figure 1 is an e evation partly in section illustrating a lamp embodying my invention;

Fig. 2 is a fragmentary section illustrating a modified form for the exterior shade;

Figs. 3, 4 and 5 are similar viewsillustrating modified forms of an interior "refleeting shade.

The source of illumination, such as incandescent lamp 1, may be mouted on a rigid support or standard 2 of any desired form; as shown, a heavy base 3 supports an ornamental body and a tubular standard 4, preferably cylindrical, in the top of which the socket or base 5 of the lamp 1 is firmly screwed. Wiring to the lamp may be housed in the hollow standard, as usual.

I prefer to maintain a sector central on the zenith of about 90 of the sphere illuminated by the lamp free of any obstruction to the light, to provide a minimum upward illumination for the indirect lighting of the room by light reflected from the ceiling, and I "prefer toshade the source of light from direct vision throughout the remainder of the sphere in which the light is central. In order to accomplish this with provision for reflecting a desired fraction of the li ht incident on the inner surfaces of the s ading means downwardly, to illuminate the region surrounding the lamp base I may provide ashade having inner reflecting surfaces 11 and an upper opening 12. The shade 10 may be of any desired ornamental material, such as a colored or translucent glass or porcelain, with ornament on the exterior surface. The interior surface 11 is reflecting, and preferably spherical or toroid in form; as shown the axis is upon and the centers of curvature are relatively near the vertical axis of the standard.

I prefer to mount this shade 10 as shown in Fig. 1 so that the centers of curvature of surfaces 11 are beneath the source of illumination, for a purpose presently to be described, and to that end I may provide a collar 13, adjustable if desired and fastened by the set screw 14 on the cylindrical portion 4, said collar 13 supporting tripod arms 15 or any suitable spider or other holder for the shade 10. As so supported, light in-' cident on the under surface 11 of the shade 10 is focused upon an annular space surrounding the axis of the standard 2 and beneath the source 1. The collar 13, if desired, may be rigidly fixed to the top of the portion 4, since adjustment of-the osition of the shade 10 is not required a ter'the lamp is assembled.

In order to deliver upward the greater part of the light for indirect lighting or at will to reflect a desired portion ofit about the base of the lamp, I provide means readily adjustable to reflect the greater part of the light through the opening 12, or to ermit the light focused by the inner sur ace of the shade 10 to be received upon the outer convex surface of an inner concave reflector adapted to disperse about the base of the lamp by secondary reflection the li ht so focused or collected. As shown in Flg. 1, an inner reflector 20, preferably as shown in the general form of a paraboloid' Any desirable construction may em-' ployed, but I prefer to provide a guide 22 on collar 13 to receive a rod 23 which in turn rigidly carries a support 25 for the reflector 20, the rod 23 being attached to and movable by means of a collar 26 sliding 'on the cylindrical portion 4 of the standard 2, and upon which it canbe adjusted and fixed by the set screw 27. In the preferred form, the reflector shade 20 may be made of blown glass substantially as illustrated in section at the left hand side of Fig. 1, the exterior wall 30 and the interior wall 31 inclosing between them a space 32 which may be sealed at the lip 33 adapted to be seated in the support 25. I

prefer to form both the interior and the exterior reflecting surfaces of the member '20 as convex surfaces of relatively great curvature continuously recurrent in the general figure of the reflector; for instance,as shown in elevation on the right hand side of Fig. 1 the surface maybe of the cushion or lozenge form shown, the walls and 31 being broken up into small quadrangles 25 each of which. has a convex surface or short radius. Other forms of reflecting surface adapted to scatter in direction light incident upon them may be employed.

The reflector 20 may be made of anyde- 80 sired material; for instance as shown at 20 in Fig. 3, it may be a solid structure of opalescent or translucent glass having polished reflecting surfaces; or as shown in Fig. 4 at 20 the interior surfaces may be 85 provided with a silvered or other mirror coating 34; and in one preferred form of such reflector, as shown in Fig. 5 at 20,

the coating 34 may occupy only the upper 1 part of the device, the lower part in the 40 region of its apex being translucent and diffusive, as by being-made of clear glass ground, or of opalescent glass.

As shown in Fig. 1, I prefer to limit the upper position of the reflector 20 so as to permit an upper annular portion 9 of the reflectin under surface of the shade 10 to receive light from the source 1 for reflection against the inner surface 11 ofthe shade 10, which is thereby kept illuminated in order 60 to display its decorative effect and prevent it from being darkened by the shadow of the reflector 20. I

In operation, if only indirect lighting reflected from the ceiling 'is desired, the collar 26 and reflector 20 are adjusted to their upper position as shown in dotted lines in Fig. 1. In this position the beam of light projected against the ceiling is reatly increased over that from usual lightmg fixtures of which I am at present aware by the powerful reflection from the inner surface of the reflector 20. The dispersive form of the concave wall 31 of the reflector aids in preventing a sharply defined spot of light on the ceiling. When the reflector 20, Fig. 5, is in use, the diffusing portion 35 is now available for direct but softened lighting around the bottom of the standard.

When it is desired to use the fixture for a diffused lightin the lower hemisphere surrounding the source, as for reading, the inner reflector is positioned as shown in full lines in Fig. 1. As thus positioned, it will be observed that the reflection from the inner surface 11 in the shade 10 on to the reflecting outer surface 30 of the reflector 20 disperses without much loss all of the light emanating from the source 1 in a zone about 30 high and lying above the horizontal plane of the upper edge of the reflector 20. Particularly when the source of light is intensely powerful and very small, as from one of the modern types of metallic filament lamp, the dispersed reflection described provides a virtual source of il1umination having a greatly increased angular magnitude and lessened intensity, and therefore much better adapted for a reading or working light than the naked filament.

In the form shown in Fig. 2, the shade 10" is provided with a conical segment or surface 11 and an upper toroid surface 9. Illumination under the lamp is by directreflection from the surface 11 when the reflector shade is in the lower position (Fig.

1), but when as illustrated, the reflector shade 20 is used, the region at the base of the lamp is lighted also by light diffused by the portion 35. Whatever the form of the reflector shade, the toroid surface 9, when the reflector shade is in the upper position as shown, is effective to return to the outer surface of the reflector shade and thence to the shade 10 enough light to illuminate the whole surface. of shade The broken lines and arrow heads on the figures show typical directions of the various reflections, as will be understood without further explanation.

1. A lighting fixture adapted for indirect lighting having a source of light, areflector adapted to partially surround the light source and a shade partially surroundlng the reflector and adapted to expose a zenith sector of the sphere of illumination, and, means adjusting the relative position of said shade and reflector whereby to permit light reflected from the shade to be dispersed by reflection from the outer surface of said reflector.

' 2. A lighting fixture adapted for indirect lighting, having a source of light, a shade relatively fixed with respect to the light source covering a zone surrounding the light source and exposing a zenith sector of the sphere of illumination, a reflector adapted to be moved into and out of surrounding relation to and beneath the light source, and means for illuminating the region beneath the reflector by reflection from the surfaces of said shade and said reflector.

3. A lighting fixture adapted for indirect lighting, having a source of light, a shade relatively fixed with respect to the light source covering a zone surrounding the light source and exposing a-zenith sector of the sphere of illumination, a reflector adapted to be moved into and out of surrounding relation to and beneath the light source, and means for illuminating the region beneath the reflector by reflection from the surfaces of said shade and said reflector, the contour of theupper portion of the shade being adapted to reflect light to the lower portion of the shade in various positions of adjustment of the reflector.

4. A lighting fixture adapted for indirect lighting, having a sourceof light, a translucent s'hade relatively fixed with respect to the light source covering a zone" surrounding the light source and exposing a zenith sector of the sphere of illumination, a reflector adapted to be moved into and out of surrounding relation to and beneath the light source, and means for illuminating the under surface of said shade in any position of said reflector.

5. A lighting fixture adapted for indirect lighting, having a source of light, a translucentshade covering a zone surrounding the light source and exposing a zenith sector of the sphere of illumination, a reflector adapted to be moved into and out of surrounding relation to and beneath the light source, and means for illuminating the under surface of said shade in any position of said reflector.

6. A lighting fixture adapted for indirect lighting, having a source of light, a'translucent shade relatively fixed with respect to the light source covering a zone surrounding the light'source and exposing a zenith sector of the sphere of illumination, a reflector adapted to be moved into and out of surrounding relation to and beneath the light source, the contour of the upper portion of the shade being adapted to reflect light to the lower portionof the shade in various I positions of adjustment of the reflector.

7 In an indirect lighting fixture a source of light, and a reflector having an outer surface made up of recurrent light dispersing convex surfaces, and an'inner surface made up of similar dispersive surfaces, and vertically adjustable means for supporting said reflector in relation to the light source whereby to reflect the light in an upward direction, in v combination with means for concentrating upon said outer surface a portion of the light from. said source.

8. A lighting fixture having a standard, a source of light and a shade having an inner surface adapted to' focus the light beneath the source and near the standard, in combination with a reflector surrounding the trate the maximum amount of light in the upper sector or in the lower sector of illumination as desired.

9. A lighting'fixture comprising a standard, a source of light thereon, and a relatively fixed downwardly reflecting shade open at the top mounted on said standard in combination with a reflector mounted for vertical movement on said standard into a position surrounding the light source, and into a lower position beneath the light source, said reflector havin an outer surface adapted to receive and isperse light reflected from the shade;

10. In a lightin fixture, a standard, a source of light t ereon, an outer shade mounted on said standard in relation to said light source, a supporting member, means adapted to slide vertically on the standard, a connection between said supporting member and sliding means, and a reflector mounted on and adapted to be positioned by said sliding means and supporting member.

11. In a lightin fixture, a standard, a source of light t ereon, an outer shade mounted on said standard in relation to said light source, .a supporting member, means adapted to slide vertically on the standard, a connection between said supporting member and sliding means, and a reflector mounted on and adapted to be positioned by said sliding means and supporting member, the upper part of the shade'havlng means to reflect light over its lower portion.

12. A reflector for'lighting fixtures made of light transmitting material and having concave and convex surfaces, and a reflecting coating on one or more of said surfaces, the region of the apex of the reflector being adapted to diffusetransmitted light and being uncoated, whereby to transmit light.

13. A reflector for lighting fixtures made of light transmitting material and having concave and convex surfaces made up of lozengeshaped recurrent light dispersing surfaces, and a reflecting coating on one or more of said surfaces, the region of the apex of the reflector being uncoated, whereby to transmit light.

Signed by me at Boston, Mass, this 15th day of October, 1917.

DAVID CROWNFIELD. 

